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SYBM: Brownian Motion, Diffusion and Beyond

SYBM 1: SYBM

SYBM 1.2: Invited Talk

Tuesday, March 8, 2005, 11:00–11:30, TU HE101

From Maxwell demon to Brownian motor — •Christian Van den Broeck — Limburgs Universitair Centrum

Can one rectifie thermal fluctuations by operating on a microscopic level? This question, first posed by Maxwell, has become very relevant in view of the advances in nanotechnology. In his lectures, Feynmann argues on the basis of a specific construction, called the ratchet with pawl, that rectification is only possible if the device is in contact with two reservoirs at different temperature. However his conclusion that one can, in this case, reach Carnot efficiency however turns out to be flawed.

We argue that the Feynmann construction is unnecessarily complicated. We present a fully microscopic model, involving only hard core interactions, that can be simulated very accurately with molecular dynamics, and that can be solved analytically by a perturbation expansion in the limit of dilute gases.

Reference: C. Van den Broeck, R. Kawai, and P. Meurs, Microscopic Analysis of a Thermal Brownian Motor, Phys. Rev. Lett. 93, 090601 (2004)